OpenXR Vulkan Example v1.1.0

Changelog:

• Added a basic fly mode to demonstrate input handling. Hit the select button to fly in the direction of the controller.
• Added MSAA support to get rid jagged edges. Up to 4x MSAA will be used if the GPU supports it.
• Fixed some general issues with how OpenXR was used. This stops some validation errors from showing up on specific systems.
• Fixed the size of the Vulkan descriptor pool.
• Fixed a portability issue that came from using strncpy_s(). This function is not available everywhere. Now the fully portable memcpy() is used instead.

Thanks to @ChristophHaag for reporting the OpenXR and Vulkan issues.